1. Field of the Invention
This invention relates to an absorbent composition useful as an absorbent for aqueous systems, including urine, particularly useful as an improved animal or pet litter composition, and useful as an absorbent for oleophilic materials such as petroleum or vegetable based oils and the like. The invention also relates to a method of making the improved absorbent composition and litter compositions containing same.
2. Description of Related Art
Many attempts have been made in the past to provide improved absorbent compositions which are acceptable for use in animal litters, particularly for domestic pets such as cats. Generally known litter compositions available today contain large amounts of clay and/or natural grass compositions. In addition to being useful as animal litter compositions, such compositions containing clays have also been suggested for use in absorbing oily materials commonly found in garage floors from automobiles. Such oleophilic or oily materials include the lubricating oils, kerosene, power steering fluids, transmission fluids and spills from gasoline and ethylene glycol antifreeze coolant compositions and spills of vegetable oils in food plants, such as when frying. Such compositions containing clays have not been entirely satisfactory and have been deficient in one or more of the characteristics and properties necessary as an effective absorbent, particuarly for animal litter applications.
The desirable characteristics of an absorbent composition for animal litters include:
(a) high absorptive ability, particularly water or high moisture absorbency PA1 (b) a reduced odor, particularly ammoniacal from urine waste products PA1 (c) lack of toxicity PA1 (d) low degree of dusting to avoid tracking and PA1 (e) low cost, economically available ingredients of the composition. PA1 (a) grinding or pulverizing the cellulosic material hulls and pulp to a finely divided state PA1 (b) mixing said finely divided cellulosic material with the starch or flour binder and with water to provide an extrudable mass PA1 (c) extruding the mass through a die (preferably under heat and steam pressure to a porous expanded texture) and PA1 (d) forming a particle, granule or pellet of the extruded mass as it leaves the die and PA1 (e) drying the resulting pellet. PA1 (1) reducing a cellulosic hull material or plant pulp to a finely divided particle size, PA1 (2) mixing said finely divided hull material, or a mixture thereof with finely divided cellulosic plant pulp, with a carbohydrate binder PA1 (3) moistening said mixture to provide a homogenous extrudable mass or dough PA1 (4) extruding the mass or dough at an elevated temperature to provide an expanded extrudate while sizing or shaping the extrudate PA1 (5) cutting the sized and shaped extrudate to the desired particle size and PA1 (6) drying the resultant particles.
Natural grasses, such as alfalfa have been employed in the past with a clay for a binder. While such natural grasses may contain some odor suppressant ability as a result of any chlorophyl present therein, alfalfa has a strong odor itself, particularly when wet. Other materials have been tried along with the alfalfa employing grain or grass straw, such as described in U.S. Pat. No. 4,258,660, which employs clay as a binder for maintaining the ingredients in a pelletized form, rather than for its moisture absorptivity property.
Other materials have been suggested in the past as a replacement for alfalfa, such as peanut hulls in U.S. Pat. No. 4,217,858, having the characteristics of a lubricant and/or binder. Among those having binder characteristics are clays and lignin such as sodium bentonite. Among the lubricants mentioned is starch. Reference is also made in the patent to processed corn cobs having been employed in the past.
In order to overcome odor problems, the use of fragrance releasing additives has been suggested as in U.S. Pat. No. 3,921,581, which incorporates consolidated particles having the property of fragrance release. The particles are composed of a minor amount of a perfume agent and major amount of a solid excipient of molded, finely divided or powdered solids of a binder and water sensitive disintegrant. The excipient may be all clay or include other finely divided cellulosic solids, such as saw dust, or chlorophyl containing solids, such as ground alfalfa. In addition to clays, the binder and water sensitive disintegrant may be water soluble or dispersible gums such as guar gum, microcrystalline cellulose or pregelatinized starch. The fragrance release composition is then blended with a porous expanded litter product prepared from equal parts by weight of ground alfalfa and gelatinized wheat flour.
In U.S. Pat. No. 3,059,615, an animal litter generally is described which is composed of acidic cellulosic materials which include dried grasses or hay, husks, sawdust, corn cob grits, excelsior and cereal hulls. The cellulosic materials are merely ground to a desirable size and sprayed with the acid solution.
Other patents generally dealing with alfalfa based animal litter with various binders, either alone or admixed with other absorbent materials are described in U.S. Pat. Nos. 4,206,718; 3,923,005; 3,972,971; 3,789,797 and U.S. Pat. No. 3,983,842, which describes other prior patents in the litter area.